1. Field of the Invention
The present invention relates to a digital still camera, and more specifically, it relates to a technology for reducing the extent to which an image becomes blurred.
2. Description of the Related Art
An image blur caused by an unsteady hand movement or the like during a photographing operation greatly detracts from the appearance of the resulting picture and thus greatly lowers the value of the photograph. The extent of such an image blur increases as the shutter speed decreases. Generally, a significant extent of image blur is said to manifest in a photograph taken by holding a 35 mm camera mounted with a photographic lens with a focal length of f [mm], if the shutter speed becomes lower than 1/f [sec]. Accordingly, various attempts have been made in the related art to reduce the extent of image blur.
Japanese Laid Open Patent Publication No. H 11-215432 discloses a digital still camera designed to reduce the image blur without having to detect any camera vibration. By taking advantage of a digital still camera feature which allows the ISO speed to be adjusted for each frame, the ISO speed level is raised if the calculated shutter speed is lower than a hand movement limit value so as to sustain a high shutter speed in this digital still camera. While the shutter speed can be sustained at a high level by raising the ISO speed, this method has a problem in that the image quality becomes poor due to noise.